The long term goal of this project is to understand the role and regulation of cP450 arachidonic acid metabolites in mammalian proximal tubule function. The proximal tubule contains the highest concentration of cP450 within the mammalian kidney and expresses minimal cyclooxygenase or lipoxygenase activity. We hypothesize that hormonally mediated release of arachidonic acid in the proximal tubule leads to cP450 mediated generation of epoxyeicosatrienoic acid (EETs) and omega/omega -1 HETEs, and these metabolites serve as bioactive agonists to regulate proximal tubule function and growth. In Specific Aim 1, we will characterize the role of cP450 arachidonic acid metabolites in the regulation of the renin angiotensin system and its control of proximal tubule transport. For these studies, we will utilize in vitro microperfusion of proximal tubules from wild type, knockout and transgenic mice. We will also investigate the direct effects of cP450 metabolites to regulate the proximal tubule sodium-hydrogen antiporter (NHE3), which is a major transport mechanism for apical sodium reabsorption in this nephron segment. Specific Aim 2 will examine mechanisms of EET signaling in the proximal tubule. These studies will investigate the mechanism by which EETs activate cleavage of membrane-associated HB-EGF. Specific Aim 3 will characterize production and biologic responses of novel cP450 arachidonic metabolites, the monoglyceride-associated EETs. These studies will examine regulation of endogenous production, their potential role as endocannabinoids and signaling mechanisms underlying mitogenic actions in renal epithelial cells.